A one-pot synthesis process was developed to prepare polyvinyl alcohol/silica (PVA/SiO2) composite microspheres. Uniform PVA/SiO2 hybrid sols were firstly obtained by in situ hydrolysis of tetraethyl orthosilicate (TEOS) in the PVA solution and then formulated into microspheres in a surfactant-free oil phase. The resultant PVA/SiO2 composite microspheres exhibited a regular spherical shape, a high dispersity and a homogenous microstructure. Their average particle diameter was determined as about 58.2 μm. The inorganic phase of the composite microspheres was identified as amorphous SiO2 with a condensation degree of about 62.4 %, and its actual content was in close agreement with the theoretical value. Moreover, the PVA/SiO2 composite microspheres were covered by apatite clusters after being soaked in simulated body fluid (SBF), indicating their good in vitro bioactivity.